It should be made perfectly clear that the stem is the axis of the plant,
that is, it bears all the other organs. Roots grow from stems, not steins
from roots, except in certain cases, like that of the Poplar mentioned
above. This was seen in the study of the seedling. The embryo consisted of
stem and leaves, and the roots were produced from the stem as the seedling
grew.

For illustration of this point, the careful watching of the cuttings
placed in water will be very instructive. After a few days, small, hard
lumps begin to appear under the skin of the stem of the broken seedling
Bean. These gradually increase in size until, finally, they rupture the
skin and appear as rootlets. Roots are always thus formed under the outer
tissues of the stem from which they spring, or the root from which they
branch. In the Bean, the roots are in four long rows, quartering the stem.
This is because they are formed in front of the woody bundles of the stem,
which in the seedling Bean are four. In the Sunflower the roots divide the
circumference into six parts. In some of my cuttings of Beans, the stem
cracked in four long lines before the roots had really formed, showing the
parenchyma in small hillocks, so to speak. In these the gradual formation
of the root-cap could be watched throughout, with merely a small lens. I
do not know a better way to impress the nature of the root on the pupil's
mind. These forming roots might also be marked very early, and so be shown
to carry onward their root-cap on the growing-point.


4. _Root-hairs_. These are outgrowths of the epidermis, or skin of the
root, and increase its absorbing power. In most plants they cannot be seen
without the aid of a microscope. Indian Corn and Oats, however, show them
very beautifully, and the scholars have already noticed them in their